This invention relates to a lamp used for a portable lighting device or the like, and also a portable lighting device including the same.
Conventionally, a lamp used for a portable lighting device emits light only when electric power is supplied. The lamp positioned inside a reflecting mirror emits light as it is connected to a power source.
In such a conventional lamp and a lighting device including the same, however, the light goes out immediately when power supply stops. As a result, the environmental circumstance and position of the lighting device cannot be recognized easily, which may cause hazards. For example, when a bicycle with a headlight stops running, an oncoming person cannot be aware of the bicycle until colliding with it. Car drivers cannot see such a bicycle at an intersection, which may cause an accident. Or it is difficult to find a lighting device in an unexpected blackout. Also, since lamps are carried and assembled into sockets by hands, if phosphorescent layers are provided on the lamp, they should be difficult to peel off.
Tb solve the above-mentioned problems, this invention provides a lamp and a lighting device including the same, and the lamp of this invention comprises a phosphorescent layer that is difficult to peel off. The layer has a long-lasting phosphorescent property, and the luminescence of the lamp continues for a certain time after turning off the light.
In order to achieve the purpose, a lamp of this invention has a phosphorescent layer comprising a phosphorescent compound and a binder resin on at least the front surface of a bulb. Addition of the binder resin can improve the strength and durability of the phosphorescent layer. Preferably 1-50 weight parts of the binder resin is added to 100 weight parts of the phosphorescent compound. When the ratio of the binder resin is less than 1 weight part, the strength and durability of the phosphorescent layer will be decreased. When the binder resin exceeds 50 weight parts, the phosphorescent property will be decreased.
In the lamp, the thickness of the phosphorescent layer is preferably from 150 to 250mg/cm2. Within this range, the illumination during regular lighting of the lamp will not be much decreased, while the phosphorescent layer will illuminate to be recognized even if the lamp is turned off.
In the lamp, the phosphorescent layer is preferably formed in the range from xc2xc to xc2xd of the bulb surface area. When the phosphorescent layer is formed at least on the front of the bulb and covers in the range from xc2xc to xc2xd of the surface area of the same bulb, the phosphorescent layer will illuminate to be recognized even if the lamp is turned off.
In the lamp, the phosphorescent pigment can be an inorganic material having a luminescent peak in the wavelength of about 350-700 nm. Light having wavelength of about 350-700 nm is included in visible light that can be recognized by human beings.
The phosphorescent pigment can comprise strontium aluminate (SrAl2O4) as the main component for cost reduction and convenience.
A portable lighting device of this invention is provided with a lamp as mentioned above inside (in front) of its reflecting mirror. The phosphorescent layer is coated on the part that is positioned forward when the lamp is in use, and the reflecting mirror of the lamp assembly is positioned behind the bulb.
The portable lighting device can be, for example, a flashlight, a headlight for a bicycle, or a head lamp.